ast

Documentation

Overview

Package ast defines the cirql abstract syntax tree: the typed pipeline, stages, and expressions a parsed query produces. Nodes are pure data; the closed Stage and Expr sets are enforced by unexported tag methods.

Index

• type BinOp
• type BinaryExpr
• type Expr
• type FieldAccess
• type FileStage
• type FilterStage
• type FlatMapStage
• type FuncCall
• type HTTPStage
• type LimitStage
• type Literal
• type MapStage
• type Mapping
• type PathSegment
• type Pipeline
• type QueryStage
• type ReduceOp
• type ReduceStage
• type SortStage
• type Stage
• type StdinStage
• type UnOp
• type UnaryExpr
• type UniqStage
• type VarRef

Types

type BinOp

type BinOp string

BinOp names a binary operator.

const (
	// OpOr is logical ||.
	OpOr BinOp = "||"
	// OpAnd is logical &&.
	OpAnd BinOp = "&&"
	// OpEq is ==.
	OpEq BinOp = "=="
	// OpNe is !=.
	OpNe BinOp = "!="
	// OpGt is >.
	OpGt BinOp = ">"
	// OpLt is <.
	OpLt BinOp = "<"
	// OpGe is >=.
	OpGe BinOp = ">="
	// OpLe is <=.
	OpLe BinOp = "<="
	// OpAdd is +.
	OpAdd BinOp = "+"
	// OpSub is -.
	OpSub BinOp = "-"
	// OpMul is *.
	OpMul BinOp = "*"
	// OpDiv is /.
	OpDiv BinOp = "/"
	// OpMod is %.
	OpMod BinOp = "%"
)

type BinaryExpr

type BinaryExpr struct {
	L  Expr
	R  Expr
	Op BinOp
}

BinaryExpr is L Op R.

type Expr

type Expr interface {
	// contains filtered or unexported methods
}

Expr is an expression evaluated against the current object. Closed via isExpr.

type FieldAccess

type FieldAccess struct{ Path []PathSegment }

FieldAccess is .a.b[] etc.; an empty Path is the identity ".".

type FileStage

type FileStage struct{ Path string }

FileStage reads JSON from a local file.

type FilterStage

type FilterStage struct{ Cond Expr }

FilterStage keeps objects for which Cond is truthy.

type FlatMapStage

type FlatMapStage struct{ Mappings []Mapping }

FlatMapStage transforms and flattens: list-valued mappings expand into multiple output objects.

type FuncCall

type FuncCall struct {
	Name string
	Args []Expr
}

FuncCall is name(args...).

type HTTPStage

type HTTPStage struct{ URL Expr }

HTTPStage fetches JSON over HTTP.

type LimitStage

type LimitStage struct{ N int }

LimitStage truncates the result set to at most N objects.

type Literal

type Literal struct{ V value.Value }

Literal is a constant value.

type MapStage

type MapStage struct{ Mappings []Mapping }

MapStage transforms each object 1:1 into a new object.

type Mapping

type Mapping struct {
	Expr Expr
	Key  string
}

Mapping is a key/expression pair in a map or flatMap stage.

type PathSegment

type PathSegment struct {
	Name   string
	IsIter bool
}

PathSegment is one step of a field access: a named field, or [] iteration.

type Pipeline

type Pipeline struct {
	Stages []Stage
}

Pipeline is a parsed cirql query: an ordered list of stages.

type QueryStage

type QueryStage struct{ Body string }

QueryStage executes a GraphQL query.

type ReduceOp

type ReduceOp string

ReduceOp names an aggregation in a reduce stage.

const (
	// OpCount counts the result set.
	OpCount ReduceOp = "count"
	// OpSum sums the argument expression over the result set.
	OpSum ReduceOp = "sum"
	// OpMin takes the minimum of the argument expression.
	OpMin ReduceOp = "min"
	// OpMax takes the maximum of the argument expression.
	OpMax ReduceOp = "max"
	// OpAvg averages the argument expression.
	OpAvg ReduceOp = "avg"
	// OpFirst returns the first object.
	OpFirst ReduceOp = "first"
	// OpLast returns the last object.
	OpLast ReduceOp = "last"
	// OpGroupBy groups objects by the argument expression.
	OpGroupBy ReduceOp = "group_by"
	// OpCollect collects the argument expression from each object into a list.
	OpCollect ReduceOp = "collect"
)

type ReduceStage

type ReduceStage struct {
	Arg Expr
	Op  ReduceOp
}

ReduceStage aggregates the result set into a single object.

type SortStage

type SortStage struct {
	Key    Expr
	IsDesc bool
}

SortStage reorders the result set by Key.

type Stage

type Stage interface {
	// contains filtered or unexported methods
}

Stage is one step in a pipeline. The set is closed via isStage.

type StdinStage

type StdinStage struct{}

StdinStage reads the pipeline input as the result set.

type UnOp

type UnOp string

UnOp names a unary operator.

const (
	// OpNot is logical negation.
	OpNot UnOp = "!"
	// OpNeg is arithmetic negation (unary minus).
	OpNeg UnOp = "-"
)

type UnaryExpr

type UnaryExpr struct {
	X  Expr
	Op UnOp
}

UnaryExpr is Op X.

type UniqStage

type UniqStage struct{ Key Expr }

UniqStage deduplicates the result set, by Key when non-nil else whole-object.

type VarRef

type VarRef struct{ Name string }

VarRef is a $name reference.